Various processes have been developed to apply coatings to glass containers for different purposes, including decoration, ultraviolet light protection, lubricity, and abrasion resistance. In a conventional glass container manufacturing process, a hot end coating is applied to an exterior surface of a formed glass container at a so-called “hot end” of an annealing lehr, immediately after the glass container is formed. An additional cold end coating is conventionally applied to the exterior surface of the glass container at a “cold end” of the annealing lehr, after the glass container has been cooled down to a temperature below the strain point of the glass by being passed through the annealing lehr. The hot end coating typically comprises a metal oxide, e.g., an oxide of tin, titanium, vanadium, or zirconium, and the cold end coating typically comprises an organic material, e.g., silicone wax, polyethylene, polyvinyl alcohol, stearic acid, oleic acid, polyurethane, polyester, polyolefin, or polyacrylic material.
A general object of the present disclosure, in accordance with one aspect of the disclosure, is to provide a process for coating an interior surface of a glass container that may be performed during or after formation of the glass container, but preferably before the glass container is annealed.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
A process for coating an interior surface of a glass container, in accordance with one aspect of the disclosure, includes: (a) forming a glass preform from a gob of molten glass at a blank molding station, (b) transferring the glass preform from the blank molding station to a blow molding station, (c) forming a glass container having a final shape from the glass preform at the blow molding station, (d) introducing a coating material into an interior of the gob of molten glass, the glass preform, or the glass container while the glass is still hot from being formed to form a coating on an interior surface thereof, and (e) annealing the glass container. The coating material comprises a suspension of nanoparticles in a liquid medium, and, when the coating material is introduced into the interior of the gob of molten glass, the glass preform, or the glass container, heat from the glass is transferred to the liquid medium to vaporize the liquid medium and form the coating on the interior surface of the gob of molten glass, the glass preform, or the glass container.
The coating material may be introduced into the interior of the gob of molten glass, the glass preform, or the glass container during one or more stages of a glass container forming process, which may involve a blow-and-blow system, a press-and-blow system, or any other forming system. For example, the coating material may be introduced into the interior of the gob of molten glass and/or the glass preform at the blank forming station at the same time or immediately after the glass preform is blown or pressed into shape. Or the coating material may be introduced into the interior of the glass preform as the preform is being transferred from the blank forming station to the blow molding station. As another example, the coating material may be introduced into the interior of the glass preform and/or the glass container at the blow molding station at the same time or immediately after the glass container is blown into its final shape. Or the coating material may be introduced into the interior of the glass container while the glass container is being transferred from the blow molding station to an annealing lehr. For example, the coating material may be introduced into the interior of the glass container while the container is being transferred from the blow molding station to a deadplate, conveyor, or another location upstream of the annealing lehr. In some cases, the coating material may be introduced into the interior of the glass container at a glass container coating system positioned in-line or offline upstream of the annealing lehr.
A process for coating an interior surface of a glass container, in accordance with another aspect of the disclosure, includes: (a) forming a glass preform having an initial shape from a gob of molten glass at a blank molding station during a blank molding stage, (b) transferring the glass preform from the blank molding station to a blow molding station during an invert stage, (c) forming a glass container having a final shape from the glass preform at the blow molding station during a blow molding stage, (d) transferring the glass container from the blow molding station to a deadplate during a takeout stage, (e) introducing a coating material into an interior of the gob of molten glass, the glass preform, or the glass container while the glass is at a temperature in the range of 200-1200° C., and then (f) annealing the glass container. The coating material comprises a suspension of nanoparticles in a liquid medium and, when the coating material is introduced into an interior of the gob of molten glass, the glass preform, or the glass container, heat from the glass is transferred to the liquid medium to vaporize the liquid medium and form a coating on an interior surface of the glass preform or the glass container. The coating material may be introduced into the interior of the gob of molten glass, the glass preform, or the glass container during the blank molding stage, the invert stage, the blow molding stage, or the takeout stage.